Acta Vet Scand. 2008 Mar 3;50:6. doi: 10.1186/1751-0147-50-6.

Circulating beta-endorphin, adrenocorticotrophic hormone and cortisol levels of stallions before and after short road transport: stress effect of different distances.

Fazio E, Medica P, Aronica V, Grasso L, Ferlazzo A.

Source

Department of Morphology, Biochemistry, Physiology and Animal Production, Unit of Veterinary Physiology, Faculty of Veterinary Medicine, University of Messina, 98168 Messina, Italy. esterina.fazio@tin.it

Abstract

BACKGROUND:

Since transport evokes physiological adjustments that include endocrine responses, the objective of this study was to examine the responses of circulating beta-endorphin, adrenocorticotrophic hormone (ACTH) and cortisol levels to transport stress in stallions.

METHODS:

Forty-two healthy Thoroughbred and crossbred stallions were studied before and after road transport over distances of 100, 200 and 300 km. Blood samples were collected from the jugular vein: first in a single box immediately before loading (pre-samples), then immediately after transport and unloading on arrival at the breeding stations (post-samples).

RESULTS:

An increase in circulating beta-endorphin levels after transport of 100 km (P < 0.01), compared to basal values was observed. Circulating ACTH levels showed significant increases after transport of 100 km (P < 0.001) and 200 km (P < 0.001). Circulating cortisol levels showed significant increases after road transport over distances of 100, 200 and 300 km (P < 0.001). An effect of transport on beta-endorphin, ACTH and cortisol variations was therefore evident for the different distances studied. No significant differences (P > 0.05) between horses of different ages and different breeds were observed for beta-endorphin, ACTH and cortisol levels.

CONCLUSION:

The results obtained for short term transportation of stallions showed a very strong reaction of the adrenocortical system. The lack of response of beta-endorphin after transport of 200-300 km and of ACTH after transport of 300 km seems to suggest a soothing effect of negative feedback of ACTH and cortisol levels.